I'm writing a series of command line tools that can read disk images and write to Acorn standard 200K SSDs.

I have a Solidisk DDFS in my Beeb, so I've make the tool able to read that format, along with the chained catalogue filesystem that Solidisk uses.

What other DFS formats are out there? How do other DFS's allow more than 31 files? How do double-density disks indicate start sectors above &3FF or lengths above &3FFFF (256K) - both of which are possible with 320K disks.

So a request: could people provide examples of disks that demonstrate these features?

Thanks!

There's some useful information about different DFS formats here:

http://mdfs.net/Docs/Comp/Disk/Format/DFS

Yeah, and I'll be using that as the basis of my coding. But without real images to test against, I won't know if I've done it right, or not

An emulator can be used to make some test images.

BeebEm lets you configure the ROMs. Just swap out the DNFS ROM for whichever DFS you want to use (and select the 1770 disc controller if it's a double density format).

Then just attach a new blank disc image, turn off write protect, and write a bunch of files to it.

That's how I tested my disc image building tools and it worked a treat!

Obviously I'm doing something wrong then...

Startup BeebEm 4.14, in BBC B emulation mode.
Hardware / Floppy Controller /Select FDC board / Watford.dll
Hardware / ROM Configuration and replace DNFS with BBC/wdfs.rom

Now a reset shows "Watford DFS 1.44"

From the file menu I can load disk or new disk, as normal. But any disk activity returns "disk fault ff at 00/00".

Am I doing something bizarrely wrong?

ETA: Yes, I'm doing something bizarrely wrong. wdfs.rom is an 8271 DFS ROM, not a 1770 ROM! I need to hunt down the right ROMS...

I've been unable to consistently get Opus DDOS to work in double density mode. I'm not sure the emulators support this, properly. When I did get it to work the image file ended up being 640K in size, which is obviously wrong.

So if anyone has a DDOS disk image I can test with...

Thanks!